The Kidney and Excretion Flashcards
1 . blood enters the kidneys through
the renal artery
2 . blood passes through capillaires in the
cortex
3 . as the blood passes throughthe capillaries, subtances are?
filtered out into long tubules that surround the capillaries (ultrafiltration)
4 . useful substances are reabsorbed back from the tubules in?
medulla and cortex (selective reabsorption)
5 . what happens to remaining unwanted substances
pass alon thr tubules along the ureter to the bladder where theyre expelled as urine
6 . the filtered blood passes through
the renal vein
ULTRAFILTRATION
what are nephrons
long tubules along with a bundle of capillaries where the blood is filtered
ULTRAFILTRATION
1 . blood from the renal artery enters
smalller arterioles in the cortex
ULTRAFILTRATION
2 . each arteriole splits into a structure called
a glomerulus
ULTRAFILTRATION
3 . ultrafiltration takes place in the glomerulus which is?
(bundle of capillaries looped inside a hollow ball called bowman’s capsule)
ULTRAFILTRATION
4 . what are affarent and efferent aretioles?
afferent: takes blood into each glomerulus
efferent: takes the filtered blood away from the glomerulus
ULTRAFILTRATION
5 . why is the blood in the glomerulus under high pressure?
efferent arteriole is smaller in diameter than the afferent arteriole
ULTRAFILTRATION
6 . the high pressure in the glomerulus leads to what
forces liquid and small molecules in the blood out of the capillary and into the Bowman’s capsule.
ULTRAFILTRATION
7 . how many layers does the liquid pass through to get into the bowmans capsule and enter the nephron tubule
3
ULTRAFILTRATION
8 . what cant pass through the basement membrane?
large proteins - so they stay in the blood.
ULTRAFILTRATION
9 . the filtrate passes along the nephron and what happens during this
useful substances are reabsorbed
ULTRAFILTRATION
10 . finally the filrare flows through
the collecting duct andpasses out of the kidney along the ureter.
SELECTIVE REABSORPTION
1 . selective reabsorption takes place as
the filtrate floes along the proximal convulated tubule through the loop of henle and along the distal convulated tubule.
SELECTIVE REABSORPTION
2 . useful substances leave the tubules of the nephrons and enter?
the capillary network wrapped around them.
SELECTIVE REABSORPTION
3 . the epithelium of the PCT wall has what to provide a large surface area?
microvili
SELECTIVE REABSORPTION
4 . useful solutes like what is absorbed along the PTC
glucose, amino acids, vitamin and some salts through diffusion and active transport.
SELECTIVE REABSORPTION
5 . what else is absorbed by diffusion
some urea
SELECTIVE REABSORPTION
6 . water enters the blood by osmosis - why?
the WP of the blood is lower than that of the filtrate. it is hen reabsorbed from the lop of hene , DCT and collecting ducts.
SELECTIVE REABSORPTION
the filtrate that remains is?
urine which passes along the ureter to the bladder.
URINE
is usually made up of?
water
dissolve salts
urea
hormones
excess vitamins
URINE
doesnt usually contain
proteins and blood cells (too big to leave)
glucose, amino acids and viteamis (theyre actively reabsorbed as theyre needed by the body)
EXAMINING NEPHRONS - CORTEX
the bundle of capillaries on the kidney tissue is
the glomerulus
EXAMINING NEPHRONS - CORTEX
the white area aroud the glomerulus is
the bowman’s capsule
EXAMINING NEPHRONS - CORTEX
small white circular areas (surrounded by squamous epithelial cells -purple blobs are the nuclei of them)
are the PCTs and the DCTs
EXAMINING NEPHRONS - MEDULLA
the white areas are
the loops of henle
EXAMINING NEPHRONS - MEDULLA
the loops of henle are surrounded by
capillaries where thered dots represent the. red blood cells.
KIDNEY DISSECTION
what equipment is needed?
scalpel, apron, lab gloves
KIDNEY DISSECTION - external
4 steps?
1 - identify renal capsule
2 - find cortex
3 - identify tubes in the indented part as renal vein, artery and ureter (artery walls are thicker than the vein)
4 - draw a sketch and label
KIDNEY DISSECTION - internal
5 steps
1 - cut the kidney in half lengthways and split it open
2 - identify cortex (light) and medulla (dark)
3 - identify renal pyramids in the medulla (contains loop of henle and collecting duct)
4 - identify the renal pelvis which connects to the ureter
5 - draw a sketch and label
CONTROLLING WATER POTENTIAL
if the water potential of the blood is too low…
more water is reabsorbed by osmosis into the blood from the tubules of the nephrons so urine is more concentrated and less water is lost during excretion
CONTROLLING WATER POTENTIAL
if the water potential of the blood is too high…
less water is reabsorbed to the body by osmisis into the blood from the tubules of the nephrons so urine is more dilute and more water is lost during excretion.
CONTROLLING WATER POTENTIAL
regulation of the water potential of the blood takes place in the…
middle and last parts of the nephron (loop of henle, distal CT and the collecting duct.)
CONTROLLING WATER POTENTIAL
the volume of water reabsorbed is controlled by?
hormones - ADH
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
the loop of henle is made up of 2 limbs which help set up the countercurrent multiplier mechanim: what are they
descending limb
ascending limb
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
1 - what happens near the top of the ascending limb?
Na+ AND Cl- ions are actively pumped out into the medulla - the ascending limb ins impermeable to water so this creates a low water potential in the medulla
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
2 - because there is a lower water potential in the medulla than in the descending limb, water….
moves out of the descening limb into the medulla by osmosis, making the filtrate more concenrared since the limb is unpermeanle to ions.
water in the blood is also reabsorbed into the blood.
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
3 - what happens near the bottom of the ascending limb?
Na+ AND Cl- ions diffuse out into the meddulla, further lowering the water potential in the medullla
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
4 - the 3 stages massively increase the ion concentration in the medulla, which does what?
lowers the water potential and causes water to move out of the collecting duct by osmosis - water is reabsorbed again by the capillary network into the blood.
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
the volume of water reabsorbed from the collecting duct into the capillary is controlled by
the changing permeability of the collecting duct
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
longer the loop of henle
the more water can be reabsorbed from the filtrate
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
longer the ascending limb
more ions are actively pumped out into the medulla
CONTROLLING WATER POTENTIAL - LOOP OF HENLE
when ions are pumped out into the medulla it creates a lower water potential in the medulla which means
water moves out of the nephron and collecting duct into the capillaries, giving a very concentrated urine.
CONTROLLING WATER POTENTIAL
monitored by cells called osmoreceptors, located
in the hypothalamus
CONTROLLING WATER POTENTIAL
when the osmoreceptors are stimulated bt low water potential in the blood, what happens?
jypothalamus sends nerve impulses to the posterior pituitary flandd which releases ADJH into the blood.
CONTROLLING WATER POTENTIAL
effect of ADH on the collecting duct and DCT?
makes their walls more permeable to water so more water is reabsorbed from them into the meddulla and the blood ny osmosis producing a small amount of concentrated urine.
CONTROLLING WATER POTENTIAL - dehydration
when dehydrated , ADH level
rises because water is lost, so it needs to be increased
CONTROLLING WATER POTENTIAL - dehydration
5 steps of rising ADH
1- water content and water potential of the blood drops
2 - detected by osmoreceptors in hypothalamus
3 - posterior pituitary is stimulated to release more ADH into the blood
4 - more ADH means the DCT and collecting duct are more permeable so more water is reabsorbed
5 - small amount of highly concentrated urine priduced, less water lost
CONTROLLING WATER POTENTIAL - hydrated
when hydrated, ADH levels
fall because water content needs to be reduced
CONTROLLING WATER POTENTIAL - hydrated
5 steps of falling ADH
1 - water content of blood rises so WP rises
2 - posterior pituitary detects it
3 - releases less ADH into the blood
4 - the DCT and collecting ducts are less permeable so less water is reabsorbed to the blood.
5 - large amount of dilute urine produced and more water is lost.
KIDNEY FAULIRE
what is kidney failure?
when kidneys cant carry out their normal funcyions because they dont work properly
KIDNEY FAULIRE
explain 2 causes of kidney failure
kidney infections - cause immflammation of the kidneys which can damage the cells and interferes with filterinf in bownmans capsule or rabsorptuon.
high blood pressure - damages glomerili as if pressure gers too high capillaries get damaged meaning large molucules like proteins can ger through the capillary walls and into the urine.
KIDNEY FAULIRE
how is kidney failure detected?
measuring glomerual filtration rate - the rate at whcih blood is filtered from the glomerulus into the bowman’s capsule
KIDNEY FAULIRE
give 4 problems caused by kidney failure
- waste priducts which would normally be removed build up in the blood
- fluids accumulate in tissues because the kidney cant remove excess water from the bloood
- balance of electrolytes in the bodybecomes unbalanced - blood may become too acidic and salt buildup cdasues water retention
- long term causes anaemia - lack of haemoglobin in the blood
KIDNEY FAULIRE
what are the 2 main treatment options for kidney failure?
renal dialysis
kidney transplant
KIDNEY FAULIRE
what is haemodialysis?
where thr pstient’s blood is passes through a dialysis machine - the blood flows on one side of a partially permeable membrane and dialysis fluid flows on the other side - so waste products can diffuse into the dialysisi tubing.
KIDNEY FAULIRE
what is peritoneal diaysis?
where dialysis fluid is put through a. tube that oasses from the iutside of a patients abdomen into their abdominal cavity - waste products diffuse across the peritoneum.
KIDNEY FAILURE
limitations of peritoneal dialysis
infection
no dialysis free days
KIDNEY FAILURE
strength of dialysis
keeps person alive until transplant
less risky than having a major surgery
KIDNEY FAILURE
where do kidney transplants come from?
new kidney has to be from same blood and tissue type, often donated from a living relative
KIDNEY FAILURE
advantages and disadvantages of transplant?
cheaper than dialysis
patient has to undergo a major operatoon and the immune system may also reject the transplants - immunosuppresant drugs are needed to suppress it.
KIDNEY FAILURE
describe the 5 steps involved in a test for pregnancy
- a stick contains monoconal aantibodies of hCG in the application area bound to a coloured bead.
- when the urine is applied to the area, any hGC will bind to the antibody on the bead
- urine will move up the test strip, carrying the beads with it
- the test strip has immobilised antibodies to hCG
- if hCG is present, the test strip changes colour as the immobilised antibody binds to any hCG attached to coloured beads.
KIDNEY FAILURE
what is gas chromotography?
the urine sample is vapourised and passed through a column containing a polymer. different substances move through the column at different speeds - substances in each urine sample separate out.
KIDNEY FAILURE
what is mass specrometry?
once substances have separated out following gas chromatography, they are converted into ions and separated absed on mass and charge. the result is analysed by a computer and compared to known substances.
